U.S. will screen for gene causing cystic fibrosis

July 21, 1991|By Mary Knudson

The government will soon launch the first national effort to screen the population for carriers of a disease-causing gene, using pilot programs to test people of child-bearing age for the gene that causes cystic fibrosis.

The National Center for Human Genome Research will give five grants totaling $1 million to conduct voluntary testing, said Eric T. Juengst, the center's director for the program on ethical, legal and social implications of mapping the human genome. The test, done with less than a drop of blood, will detect 90 percent of people who are carriers of the mutated gene.

The project is the first of what is expected to be many widespread applications of screening for genes. The screening is based on knowledge that will come from a 15-year effort under way to identify all human genes.

"It is seen as kind of precedent-setting, with wide application," Dr. Juengst said of the testing. "We'll do pilot studies to see what is the best way to do it." The 32 grant applications include proposals to test members of health maintenance organizations, women who seek prenatal care and their partners, or those who seek genetic counseling, he said.

One in every 25 Caucasians is a carrier of the cystic fibrosis gene. Blacks and Asians have a lower risk.

When both parents carry the gene, there is a one-in-four chance that their children will inherit both parents' mutated cystic fibrosis gene and develop the disease. Cystic fibrosis causes thick mucous-like liquid to accumulate in the lungs and other organs and is usually fatal by the time a person reaches the late 20s.

Johns Hopkins physicians have applied for one of the pilot screening grants, according to Dr. Haig Kazazian, a professor of pediatrics. A limitation of the test is that there are some 90 different mutations of the cystic fibrosis gene, he said. The test will screen for the 16 most common variations of the gene that cause 90 percent of cystic fibrosis.

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